Solid dispersions advantages

With the PGSS process, micronized drugs and drug/PEG 4000 samples were prepared in a new way, which has some advantages over conventional methods for the micronization of pure drugs and for drug/carrier solid dispersion preparation, namely fusion methods and solvent processes. 

FIGURE 18.1 Advantages of a solid dispersion formulation, as compared to conventional capsule or tablet formulations, for enhancing dissolution rate, and consequent bioavailability of poorly water-soluble drugs. (From Serajuddin A. T. M. 19991 Pharm ScB8 1058-1066. With permission.)... 

Among the advantages of solid dispersions are the rapid dissolution rates that result in an increase in the rate and extent of the absorption of the drug, and a reduction in presystemic metabolism. This latter advantage may occur due to saturation of the enzyme responsible for biotransformation of the drug, as in the case of 17-p-estradiol or inhibition of the enzyme by the carrier, as in the case of morphine-tristearin dispersion. ... 

As mentioned previously, the drug may be present in one of several forms in the final product. The advantages and disadvantages of each form have been discussed in both injection molding and melt extrusion systems. Solid dispersion systems may be more stable and more easily processed than solid solution systems, but solid solution systems may be produced that are transparent and have increased bioavailability of poorly soluble compounds. Figs. 3 and 4 show the X-ray diffraction patterns for a polymer film containing lidocaine. The absence of the lidocaine peaks in the extruded samples, and the reported... 

In aqueous dispersion media, the preparation of high solids dispersions that are stabilized electrostatically is often fui d by the gel-hke nature of the product. This is a consequence of the interactions between the double layers surrounding each particle. No comparable increase is evident in the viscosity of sterically stabilized dispersions at high solids content. Of course, in certain applications, such as in paints, the rheological properties exhibited by electrostatically stabilized dispersions at high solids may be a decided advantage rather than a drawback. 

Compared to conventional CR formulation technologies, hot-melt extrusion (HME) offers several potential technical and business advantages. HME can be used to simultaneously generate an amorphous solid dispersion (ASD) and CR/ASD behavior, providing unique release profiles for low solubility molecules. It is also a convenient trend that a number of polymers used to generate... 

Bubbles can only affect the low-frequency part of the acoustic spectra (below 10 MHz). The frequency range 10-100 MHz is available for particle characterization even in the bubbly liquids. Acoustic spectrometers can both sense bubbles and characterize particle size. We can confirm this conclusion with thousands of measurements performed with hundreds of different systems. Sensitivity to bubbles, in fact, is an important advantage of acoustics over electroacoustics. The presence of bubbles may affect the properties of the solid dispersed phase. For instance, bubbles can be centers of aggregation, which makes them an important stability factor. 

Polymer dispersions (in non-solvent liquids, usually water) have much lower viscosities than solutions with the same polymer content. So great is the disparity in viscosities that a 50% solids dispersion may have a considerably lower viscosity than a 10% solution. Such dispersion or suspension adhesives, often called emulsion adhesives or even more loosely water-based adhesives , combine the advantages of a high solids content with low inflammability and toxicity hazard, but suffer from long drying times (see Emulsion and dispersion adhesives). Their use on non-porous substrates is restricted in a similar way to that of solution adhesives. 

Theoretical Considerations Regarding Solid Dispersions 2.3.1 Solubility Advantage of the Amorphous Form... 

II. Theoretical demonstration. J Non-Cryst Solids 320(l-3) 9-20 Ayenew Z, Paudel A, Van den Mooter G (2012) Can compression induce demixing in amorphous solid dispersions A case study of naproxen-PVP K25. Eur J Pharm Biopharm 81(1) 207-213 Babu NJ, Nangia A (2011) Solubility advantage of amorphous dmgs and pharmaceutical cocrystals. Cryst Growth Design 11(7) 2662-2679... 

The addition of MgO leads to the formation of a naiTow range of solid solutions at high temperamre, which decompose to precipitate inclusions of tetragonal Zr02 dispersed in cubic zirconia. The material, which functions as a solid electrolyte, has the added advantage that the inclusions stop the propagation of any cracks which may arise from rapid temperature change. 

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